Rational two-round modification for developing isopeptide bond-containing antimicrobial peptide with enhanced...

Area of Science:

• Antimicrobial Peptides
• Drug Discovery
• Molecular Biology

Background:

• The antimicrobial peptide CPF-7 exhibits potent activity but causes high hemolysis.
• Modifications are needed to improve its therapeutic index and stability for clinical applications.

Purpose of the Study:

• To develop a modified antimicrobial peptide with enhanced antibacterial activity, reduced hemolysis, and improved stability.
• To investigate the therapeutic potential of novel peptide analogs against multidrug-resistant bacteria.

Main Methods:

• Introduction of isopeptide bonds and amino acid substitutions to create and screen peptide analogs.
• Evaluation of antibacterial activity (MIC), hemolysis (MHC20), serum stability (t1/2), and resistance induction.
• In vitro and in vivo studies on biofilms, persisters, and skin wound infections.
• RNA sequencing to elucidate the antibacterial mechanism.

Main Results:

• The lead peptide IP2-D4 demonstrated potent activity against multidrug-resistant Pseudomonas aeruginosa and Acinetobacter baumannii (MIC = 4-8 μg/mL).
• IP2-D4 exhibited reduced hemolysis (MHC20 = 256 μg/mL) and high serum stability (t1/2 = 2.932 h).
• Effective eradication of bacterial persisters and biofilms, low resistance induction, and significant in vivo efficacy in treating skin and catheter-associated infections were observed.
• Mechanism involves up-regulation of bacterial membrane genes and membrane destruction.

Conclusions:

• The modified peptide IP2-D4 represents a promising therapeutic candidate with an improved safety profile and potent efficacy against challenging bacterial infections.
• IP2-D4's mechanism of action involves targeting bacterial membranes, suggesting a low propensity for resistance development.